Our objective is to produce a lung cancer model which will allow bold, innovative surgical and non-operative therapeutic and diagnostic trials relevant to the management of bronchogenic cancer in humans. Among the things this model is to permit in animals are critical evaluations of current concepts of pulmonary resection for human cancer, the development and testing of new positive imaging scintiscan approaches, serial correlative endoscopic and histopathologic observations and immunologic research. While the aim of this proposal is primarily to produce the model, our long term goal is primarily to study cancer in humans, utilizing the animal model for approaches which are not yet suitable for trials in man. Inbred beagles will have weekly flexible fiberoptic bronchoscopy for specifically localized application of topical 3,4-Benzopyrene bound to a suspension of Fe2O3 dust. The central orifice of a major bronchus known to be uniquely free of bronchial collaterals to other lobes has been selected. Two groups of dogs will have chronic immunosuppression with azathioprine and prednisone at moderate and high dose levels, and a third group will not be immunosuppressed. While previous animal models have generally used chemical carcinogens either diffusely instilled or systemically injected which have produced multicentric tumors unlike bronchogenic cancer in man, our method will likely produce specifically localized lung cancers placed like many which are found in humans. Evaluation will include bronchophotography, serial biopsies and cytologic washings. We expect to produce canine lung cancers which will metastasize, invade and perhaps develop and grow in a somewhat predictable, reproducible manner.